“The volunteers started chatting about the yellow balls they kept seeing in the images of our galaxy, and this brought the features to our attention,” said Grace Wolf-Chase of the Adler Planetarium in Chicago.

A new ScienceCast video examines “yellow balls” and their role in star formation.Play it

The Milky Way Project is one of many “citizen scientist” projects making up the Zooniverse website, which relies on crowdsourcing to help process scientific data. For years, volunteers have been scanning Spitzer’s images of star-forming regions—places where clouds of gas and dust are collapsing to form clusters of young stars. Professional astronomers don’t fully understand the process of star formation; much of the underlying physics remains a mystery. Citizen scientists have been helping by looking for clues.

Before the yellow balls popped up, volunteers had already noticed green bubbles with red centers, populating a landscape of swirling gas and dust. These bubbles are the result of massive newborn stars blowing out cavities in their surroundings. When the volunteers started reporting that they were finding objects in the shape of yellow balls, the Spitzer researchers took note.

The rounded features captured by the telescope, of course, are not actually yellow, red, or green—they just appear that way in the infrared, color-assigned images that the telescope sends to Earth. The false colors provide a way to humans to talk about infrared wavelengths of light their eyes cannot actually see.

“With prompting by the volunteers, we analyzed the yellow balls and figured out that they are a new way to detect the early stages of massive star formation,” said Charles Kerton of Iowa State University, Ames. “The simple question of ‘Hmm, what’s that?’ led us to this discovery.”

A thorough analysis by the team led to the conclusion that the yellow balls precede the green bubbles, representing a phase of star formation that takes place before the bubbles form.

“Basically, if you wind the clock backwards from the bubbles, you get the yellow balls,” said Kerton.

An artist’s concept shows how “yellow balls” fit into the process of star formation.

Researchers think the green bubble rims are made largely of organic molecules called polycyclic aromatic hydrocarbons (PAHs). PAHs are abundant in the dense molecular clouds where stars coalesce. Blasts of radiation and winds from newborn stars push these PAHs into a spherical shells that look like green bubbles in Spitzer’s images. The red cores of the green bubbles are made of warm dust that has not yet been pushed away from the windy stars.

Essentially, the yellow balls mark places where the PAHs (green) and the dust (red) have not yet separated. The superposition of green and red makes yellow.

So far, the volunteers have identified more than 900 of these compact, yellow features. The multitude gives researchers plenty of chances to test their hypotheses and learn more about the way stars form.

Meanwhile, citizen scientists continue to scan Spitzer’s images for new finds. Green bubbles. Red cores. Yellow balls. What’s next? You could be the one who makes the next big discovery. To get involved, go to zooniverse.org and click on “The Milky Way Project.”

The icy moon Europa is perhaps the most tantalising destination in our solar system. Scientists have been trying for years to kickstart a mission to Jupiter’s most enigmatic moon, with very Earth-like concerns over costs keeping missions grounded until now.

The European Space Agency’s ambitious mission to Jupiter, JUICE, will visit its fire-and-ice moons – volcanic Io, icy Europa, giant Ganymede, and cratered Callisto – in the 2030s. But it will only provide a glimpse of Europa’s surface from a couple of close flybys. With the announcement of the NASA-led Europa Clipper mission, now it looks like a much closer inspection of Europa is on the cards.

It’s hard to overstate the excitement among planetary scientists, after so many years of waiting in the wings while all eyes were on Mars. This is truly a quest to understand what makes a world habitable.

A Watery World

Europa is the smallest and smoothest of the four Galilean moons. At 1,940 miles across, it is roughly a quarter of the size of Earth, composed of a mixture of ices and rocks. When the Galileo spacecraft flew over Europa in the 1990s, it uncovered evidence of a global sub-surface ocean: vast, deep, dark waters hidden beneath the ice crust.

The water doesn’t freeze completely because it’s constantly kneaded by powerful tidal forces as the moon orbits around Jupiter once every 3.5 days. What’s more, the ocean is believed to be in direct contact with the surface ices and the moon’s silicate mantle, which brings together all the necessary ingredients for a habitable environment: liquid water, a source of energy, and a source of minerals/nutrients. We know that life on Earth can exist in even the most extreme environmental conditions (for example, bacteria known asextremophiles), so maybe – just maybe – Europa’s hidden ocean could support life.

Neither JUICE nor Clipper will reach the surface or the ocean below – that’s too great a technological challenge for now. But if habitable conditions for life are discovered beyond Earth, particularly somewhere as far from the Sun as Jupiter and its moons, this could mean that habitable conditions are commonplace throughout our universe.

We must begin to explore Europa via orbital reconnaissance: to image and perform spectral analysis of the composition and geology of the surface, and the radiation, magnetic, electric and plasma fields that sweep across it. With ice penetrating radar we can probe through the icy crust, even as far as the hidden ocean to understand the forces that shape this icy world.

Europa’s fractured and cracked surface is geologically quite young, and relatively crater-free. The structures that the Galileo probe observed from orbit suggest freeze-melt processes that trap icy burgs into frozen seas, creating the scarred patterns known aschaos terrain. Dark parallel ridges criss-cross the bright planes, possibly due to tectonics or other geologic processes.

Most surprising was Hubble’s observations in 2012, which showed evidence of huge plumes or geysers erupting tens of kilometres over Europa’s south pole, potentially contributing to a very thin atmosphere. If we could directly sample those plumes we might just get a glimpse of the composition of the deep ocean.

Sooner Rather Than Later

So for all these reasons and more, Europa remains the highest priority target for a future mission. That there are two missions to the Jupiter system stems from years of study within NASA and ESA. At one point a joint mission, the Europa-Jupiter System Mission, was planned but was not taken forward due to funding constraints.

The Jupiter Icy Moon Explorer, JUICE, and its instruments. ESA

Today, JUICE is full-steam ahead, the project having passed through a full study and definition phase towards now building the spacecraft. If all goes to plan it would launch in 2022 and reach Jupiter in 2030. After two years of multiple fly-bys exploring Jupiter, its moons, rings and magnetosphere, it will become humankind’s first orbiter of an icy moon, targeting Ganymede in late 2032. If NASA’s recently announced funding is confirmed Europa Clipper may proceed even faster, using a new rocket (the Space Launch System) to propel it towards Europa in only a few years, potentially arriving just before or even at the same time as JUICE.

Clipper will conduct multiple flybys of Europa (maybe 45 or more over three years) without entering orbit directly, but will provide the high-resolution reconnaissance necessary to ultimately choose a landing site for some future robotic explorer. Although that future landing mission is beyond the funding horizon right now, it’s exciting to think that we’ll one day see images from that icy and harsh environment, with Jupiter suspended in the black skies above.

17. Which means that there are ones much, much bigger than little wimpy sun. Just look at how tiny and insignificant our sun is:

19. But none of those compares to the size of a galaxy. In fact, if you shrunk the Sun down to the size of a white blood cell and shrunk the Milky Way Galaxy down using the same scale, the Milky Way would be the size of the United States:

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The Antarctic ozone hole reached its annual peak size on Sept. 11, according to scientists from NASA and the National Oceanic and Atmospheric Administration (NOAA). The size of this year’s hole was 24.1 million square kilometers (9.3 million square miles) — an area roughly the size of North America.

The single-day maximum area was similar to that in 2013, which reached 24.0 million square kilometers (9.3 million square miles). The largest single-day ozone hole ever recorded by satellite was 29.9 million square kilometers (11.5 million square miles) on Sept. 9, 2000. Overall, the 2014 ozone hole is smaller than the large holes of the 1998–2006 period, and is comparable to 2010, 2012, and 2013.

With the increased atmospheric chlorine levels present since the 1980s, the Antarctic ozone hole forms and expands during the Southern Hemisphere spring (August and September). The ozone layer helps shield life on Earth from potentially harmful ultraviolet radiation that can cause skin cancer and damage plants.

The Montreal Protocol agreement beginning in 1987 regulated ozone depleting substances, such as chlorine-containing chlorofluorocarbons and bromine-containing halons. The 2014 level of these substances over Antarctica has declined about 9 percent below the record maximum in 2000.

“Year-to-year weather variability significantly impacts Antarctica ozone because warmer stratospheric temperatures can reduce ozone depletion,” said Paul A. Newman, chief scientist for atmospheres at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The ozone hole area is smaller than what we saw in the late-1990s and early 2000s, and we know that chlorine levels are decreasing. However, we are still uncertain about whether a long-term Antarctic stratospheric temperature warming might be reducing this ozone depletion.”

The graphs above show the progress of the 2014 ozone hole. The gray shading indicates the highest and lowest values measured since 1979. The red numbers are the maximum or minimum observed values. The stratospheric temperature and the amount of sunlight reaching the south polar region control the depth and size of the Antarctic ozone hole. [more]

Scientists are working to determine if the ozone hole trend over the last decade is a result of temperature increases or chorine declines. An increase of stratospheric temperature over Antarctica would decrease the ozone hole’s area. Satellite and ground-based measurements show that chlorine levels are declining, but stratospheric temperature analyses in that region are less reliable for determining long-term trends.

Scientists also found that the minimum thickness of ozone layer this year was recorded at 114 Dobson units on Sept. 30, compared to 250-350 Dobson units during the 1960s. Over the last 50 years satellite and ground-based records over Antarctica show ozone column amounts ranging from 100 to 400 Dobson units, which translates to about 1 millimeter (1/25 inch) to 5 millimeters (1/6 inch) of ozone in a layer if all of the ozone were brought down to the surface.

The ozone data come from the Dutch-Finnish Ozone Monitoring Instrument on NASA’s Aura satellite and the Ozone Monitoring and Profiler Suite instrument on the NASA-NOAA Suomi National Polar-orbiting Partnership satellite. NOAA measurements at South Pole station monitor the ozone layer above that location by means of Dobson spectrophotometer and regular ozone-sonde balloon launches that record the thickness of the ozone layer and its vertical distribution. Chlorine amounts are estimated using NOAA and NASA ground measurements and observations from the Microwave Limb Sounder aboard NASA’s Aura satellite.

NASA and NOAA are mandated under the Clean Air Act to monitor ozone-depleting gases and stratospheric depletion of ozone. Scientists from NASA and NOAA have been monitoring the ozone layer and the concentrations of ozone-depleting substances and their breakdown products from the ground and with a variety of instruments on satellites and balloons since the 1970s. These observations allow us to provide a continuous long-term record to track the long-term and year-to-year evolution of ozone amounts.

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High above Earth, more than 20 miles above sea level, a diaphanous layer of ozone surrounds our planet, absorbing energetic UV rays from the sun. It is, essentially, sunscreen for planet Earth. Without the ozone layer, we would be bathed in dangerous radiation on a daily basis, with side effects ranging from cataracts to cancer.

People were understandably alarmed, then, in the 1980s when scientists noticed that manmade chemicals in the atmosphere were destroying this layer. Governments quickly enacted an international treaty, called the Montreal Protocol, to ban ozone-destroying gases such as CFCs then found in aerosol cans and air conditioners. On September 16, 1987, the first 24 nations signed the treaty; 173 more have signed on in the years since.

Fast forward 27 years. Ozone-depleting chemicals have declined and the ozone hole appears to be on the mend. The United Nations has called the Montreal Protocol “the most successful treaty in UN history.” Yet, despite Montreal’s success, something is not … quite … right.

A new ScienceCast video looks into the surprising abundance of carbon tetrachloride in the ozone layer. Where is it coming from?

A new study by NASA researchers shows that a key ozone-depleting compound named carbon tetrachloride (CCl4) is surprisingly abundant in the ozone layer.

“We are not supposed to be seeing this at all,” says NASA atmospheric scientist Qing Liang.

Between 2007 and 2012, countries around the world reported zero emissions of CCl4, yet measurements by satellites, weather balloons, aircraft, and surface-based sensors tell a different story. A study led by Liang shows worldwide emissions of CCl4 average 39 kilotons per year, approximately 30 percent of peak emissions prior to the international treaty going into effect.

In the 1980s, chlorofluorocarbons became well-known to the general public. As the ozone hole widened, “CFC” became a household word. Fewer people, however, have heard of CCl4, once used in applications such as dry cleaning and fire-extinguishers.

“Nevertheless,” says Liang, “CCl4 is a major ozone-depleting substance. It is the 3rd most important anthropogenic ozone-depleting compound behind CFC-11 and CFC-12.”

Click to learn about the chemistry of ozone depletion from the US Environmental Protection Agency.Web link

Levels of CCl4 have been declining since the Montreal Protocol was signed, just not as rapidly as expected. With zero emissions, abundances should have dropped by 4% per year. Instead, the decline has been closer to 1% per year.

To investigate the discrepancy, Liang and colleagues took CCl4 data gathered by NOAA and NASA and plugged it into a NASA computer program, the 3-D GEOS Chemistry Climate Model. This sophisticated program takes into account the way CCl4 is broken apart by solar radiation in the stratosphere as well as how the compound can be absorbed and degraded by contact with soil and ocean waters. Model simulations pointed to an unidentified ongoing current source of CCl4.

“It is now apparent there are either unidentified industrial leakages, large emissions from contaminated sites, or unknown CCl4 sources,” says Liang.

Another possibility is that the chemistry of CCl4 might not be fully understood. Tellingly, the model showed that CCl4 is lingering in the atmosphere 40% longer than previously thought. “Is there something about the physical CCl4 loss process that we don’t understand?” she wonders.